U.S. Attorney General Eric Holder speaks about gun violence to the U.S. Conference of Mayors winter meeting in Washington, on Friday, Jan. 18, 2013. Holder said on Friday that President Barack Obama acted within his legal authority when Obama unveiled a set of executive actions to try to reduce gun violence.

By Phil Mattingly and William Selway, Bloomberg

Posted Jan. 18, 2013, at 7:19 p.m.

WASHINGTON — Attorney General Eric Holder said Friday that President Barack Obama’s proposals to ban high-capacity magazines and assault weapons are “essential” to any effort to combat gun attacks.

Holder called on Congress to swiftly pass an expansion of the background check system for gun purchases and pushed lawmakers vote for Obama’s other gun proposals as well.

“These measures represent essential parts of any serious, comprehensive effort to eradicate violence,” Holder, 61, said at a meeting of the U.S. Conference of Mayors in Washington.

A month after the shooting that killed 20 students and six educators at a Connecticut elementary school, Obama this week laid out proposals to regulate guns. He asked Congress to pass legislation to reinstate a ban on sales of assault weapons, limit high-capacity ammunition clips, and mandate background checks for all gun buyers.

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Lawmakers, in the midst of dealing with deadlines to fund the government, prevent across-the-board cuts to defense spending and raise the debt ceiling, have given mixed reviews to Obama’s proposals. While some Democrats in both chambers have embraced the push and planned legislation and hearings, Republicans, who control the House, and Senate Democrats facing re-election have taken a more reluctant approach and voiced concern about the proposals threatening individual’s rights.

New York Mayor Michael Bloomberg, a proponent of tougher gun laws and co-chairman of Mayors Against Illegal Guns, also urged city leaders to press Congress to pass Obama’s proposals. The measures would reduce gun crimes and suicides, he said.

After Colorado expanded its background check requirements, fewer guns from the state turned up at crime scenes in other states, he said. The 1994 assault weapon ban also lessened their use in crimes before it was allowed to expire in 2004, he said.

“We need to tell our members of Congress that they’ve got to stand up for sensible gun laws and if they do that, we will stand up for them,” Bloomberg said at the mayors’ meeting. “And if they don’t, we will stand up for whoever runs against them — because that’s exactly what the NRA is trying to do.”

The mayor is founder and majority owner of Bloomberg News parent Bloomberg LP.

Holder acknowledged the difficulty some lawmakers face in voting to tighten regulations on guns as they prepare for 2014 re-election races. He asked them to support the proposal despite the risk.

“There come times when those of us who are in elected or appointed positions must put the interests of those we are privileged to serve above that which might be politically expedient or professionally safe,” Holder said.

Obama, when he unveiled the proposals on Jan. 16, also announced 23 executive actions related to guns, many of which the Justice Department is required to implement. Those actions require Holder to review of the categories of people barred from purchasing guns and issue reports on lost or stolen guns and new gun safety technologies.

The actions have drawn Republican criticism for circumventing the legislative process. Sen. Marco Rubio, R-Fla., said in a statement that Obama was “abusing his power by imposing his policies via executive fiat instead of allowing them to be debated in Congress.”

Holder defended Obama’s move.

“Not one of the Executive Orders — contrary to what a few have said — impinges upon anyone’s Second Amendment rights or is inconsistent with the historical use of executive power,” Holder said.